Hi Guys,
I need your help to find progressive rate spring with an 18mm I.D. and length of approx 80mm. This is actually not for RC - I have a sim-racing rig with a set of pedals that use an RC shock on the brake pedal. The stock spring is fairly light and non-progressive so I'd like to experiment with some other options. Hopefully this is an easy question for you folks in the know Here is a pic of the pedal set in question so you can see what I'm on about.

Anyone? I swear I am trying to search and track down this info myself but it seems that all I can find in terms of spring specs is the model they are suited for and unfortunately that doesn't help me. I'd really appreciate any help you can offer. Thanks.

Thanks guys. Still no joy I'm afraid. I can find regular linear compression springs close enough to spec but no luck on the progressive springs. Oh well, not to be I guess. I appreciate the help though.....